There are known oxygenators constructed to perform gas exchange by use of a multiplicity of hollow fiber membranes. U.S. Pat. No. 6,503,451 describes an example of such an oxygenator.
This oxygenator includes a housing, a hollow fiber membrane bundle received in the housing, blood-inlet and blood-outlet ports, and gas-inlet and gas-outlet ports so that gas exchange, i.e. oxygenation and carbon dioxide removal, is performed between the blood and gas through the hollow fiber membranes.
In oxygenators, it is possible for bubbles to exist in the blood coming entering the blood inlet port. In such a case, bubbles should preferably be removed by the hollow fiber membrane bundle.
However, the hollow fiber membrane bundle is designed to efficiently effect gas exchange and is not specifically designed or intended to remove bubbles. Thus, a problem exists in that bubbles are not fully removed by the hollow fiber membrane bundle. As a result, bubbles remaining in the blood are discharged out of the blood outlet port and carried with the blood downstream of the oxygenator. For this reason, it is a known practice to provide an arterial filter on an arterial line between the oxygenator and the patient for purposes of removing bubbles.